The First Command Financial Services Guide to TSP G Fund vs. C Fund Safety

Each fund guards against a different loss

The G Fund holds special US Treasury securities that don't trade on the market, so its principal can't fall. Its interest rate resets every month, which means it follows Treasury rates up and down. You give up growth to get that steadiness.

The C Fund tracks the S&P 500, the 500 largest US companies. In past bear markets it has fallen by a third or more. That loss stays on paper unless you sell, and selling is the step that makes it permanent.

So G protects the dollars you hold, and C protects what those dollars can buy in 20 years. Ruth, the widow this article follows, already owns something G-like. Her $33,000 SBP annuity rises with cost-of-living adjustments and covers $33,000 ÷ $45,000, about 73%, of her spending.

Option 1: all in the G Fund, and what it costs at 67

Going all in G protects one thing: principal. Nothing in the fund can lose value, so it suits money you'll spend within about 5 years.

At 67, though, Ruth has 25 years or more ahead of her. Assume 3% inflation, for illustration. Her $12,000 of yearly draws becomes about $16,100 in 10 years. G returns follow Treasury rates, and nobody can promise they'll stay ahead of prices.

A $600,000 balance in G would hold 50 years of Ruth's $12,000 draws. That's far more safety than she can use, and all of it sits exposed to rising prices.

There's a behavior trap too. Once Ruth is in G, moving back after stocks have risen feels like buying high. So many people never return, and a cushion meant to last 5 years quietly becomes the whole portfolio.

Option 2: all in the C Fund, and who pays when stocks fall

A 30% drop on $600,000 is $180,000, for illustration. A stock fund has no floor under its price, so a withdrawal taken after a fall can return fewer dollars than went in. That's the plain risk of the C Fund.

Withdrawals add a second problem. The TSP takes each withdrawal pro rata, meaning a slice from every fund you hold. With 100% in C, every withdrawal in a slump sells stock at a low price.

Required minimum distributions (RMDs) are the yearly amounts the IRS forces out of tax-deferred accounts. They start at age 73, or age 75 if you were born in 1960 or later. They arrive on a schedule whatever the market is doing, and you can't skip one in a bad year.

All C works for a working veteran who isn't drawing anything. For Ruth, it means her slump years get paid for with the cheapest shares she'll ever sell.

How much G Fund do Ruth and Gail each need?

Ruth needs about $60,000 in the G Fund and Gail about $150,000, which is 5 years of the draws their annuities don't cover. The rest stays in the C Fund. One difference, rent, makes Gail's cushion 2.5 times larger than Ruth's.

A hypothetical household, Ruth, 67, gets a $33,000 SBP annuity and spends $45,000 a year in her paid-off house. Her $600,000 sits in an inherited TSP beneficiary account ($300,000) and an IRA ($300,000). The gap is $45,000 − $33,000 = $12,000 a year. Five years is $12,000 × 5 = $60,000 in G, leaving $540,000 in stocks.

Gail has the same $600,000 and the same annuity, but she rents for $1,500 each month. Rent adds $18,000 a year, so she spends $63,000 and draws $63,000 − $33,000 = $30,000. Her cushion is $30,000 × 5 = $150,000, leaving $450,000 in stocks.

Now stocks fall 30%, for illustration. Ruth's $540,000 loses $162,000. Gail's $450,000 loses $135,000. Both still hold 5 years of draws in G, so neither sells stock to pay bills. We skipped income tax on withdrawals here so you can check each sum by hand.

Because withdrawals come out pro rata, Ruth follows each one with an interfund transfer (IFT), which moves money between funds inside the TSP. The IFT resets her beneficiary account to 20% G and 80% C ($60,000 of $300,000), so the net sale comes from G. IFTs aren't taxable. The other route is holding the cushion as cash in her $300,000 IRA.

All-G holds 50 years of Ruth's draws but leaves all $600,000 exposed to inflation, while the split keeps 5 years safe and $540,000 growing. If stocks fell 40% instead of 30%, the split's paper loss would grow to $216,000, but the 5 years of draws would stay safe.

Decision rule: hold about 5 years of the withdrawals your pension or SBP annuity doesn't cover in the G Fund, and don't move the stock share into G after a drop of 20% or more. Refill G from stock funds only at the yearly review or after a recovery.

What age changes the split between G and C?

Age matters less than whether you're drawing money yet. A veteran who retired at 42 and works a second career can keep the G cushion near zero for now, while Ruth, at 67, draws every year and needs about 5 years of those draws in G.

Marriage changes the math. A couple with two pensions or two Social Security checks covers more spending with guaranteed income, so their gap and their cushion shrink. A widow like Ruth has one guaranteed check and pays single-filer tax rates on her withdrawals.

Balance size moves it most. A $150,000 balance funding $20,000 of draws needs most of it in G. A $2 million balance funding $12,000 of draws needs only a small share.

So who does each option fit? All-G fits money needed within 5 years, or someone who would truly sell in a slump. All-C fits a working veteran with no withdrawals. The split fits retirees drawing income.

One honest limit: a G Fund cushion does little for someone with no pension or annuity who needs most of the balance within a few years. This page also leaves out the F, S, I and L Funds.

Moving to the G Fund after a drop is the timing that hurts

Too late is the costly one. If Ruth's $540,000 in C falls 20% to $432,000 and she switches to G, the $108,000 paper loss becomes permanent. Selling at the wrong moment is the risk First Command Financial Services puts ahead of any forecast.

Too early costs less visibly. Moving to G at 55 for money needed at 75 gives up 20 years of possible stock growth.

Wrong order is quieter. Taking the year's withdrawal in a down month without rebalancing afterward means the sale comes out of C.

Then there's paperwork. An IFT entered as 100% G moves the whole balance, not just the next withdrawal. Ruth's $240,000 in C would land in G, and if stocks rose 5% before she fixed it, for illustration, she would miss $12,000. If it was her second IFT of the month, the fix waits until next month, because further transfers can only go into G.

Ruth's son usually raises it first

After a week of crash headlines, the adult child calls and asks whether Mom should "get safe." Ruth can show him one number: $60,000, which is 5 years of her draws already sitting in G. Then they can agree that no fund change happens in the same week as a drop of 20% or more. Ruth writes that rule into her plan. When the next scary headline arrives, the answer was settled months ago, on paper, with her son's name next to hers.

How long does it take to set the split up in the TSP?

Setting the split up takes about a week from the first calculation to a confirmed trade, and most of that is waiting. The math takes 10 minutes, the transfer takes another 10, and the TSP confirms the trade a business day later.

Before you log in, do four small sums. List guaranteed income ($33,000 SBP). List yearly spending ($45,000). Subtract to find the gap ($12,000). Multiply by 5 for the cushion ($60,000).

Then work through the TSP in order. First, log in to My Account and check balances by fund in the beneficiary participant account. Second, submit one IFT setting 20% G and 80% C. Third, confirm the trade a business day later. Fourth, after each withdrawal, recheck the percentages and rebalance. Fifth, refill G to 5 years once a year.

Keep one of the 2 monthly IFTs unused as a spare. If you mistype a percentage, that spare is how you fix it without waiting a month.

The part of the G Fund vs. C Fund choice worth an hour with First Command Financial Services

You can compute the gap, size the cushion and submit the IFT on your own. A first conversation with First Command Financial Services earns its time on the harder questions: how RMDs from the inherited TSP and the IRA, Social Security timing and taxes change the size of the cushion, and what the written rule says should happen after a 20% drop.